Eco-friendly hydrolate-based seed priming: a novel strategy to improve wheat germination under salt stress
摘要
Salinity is a major abiotic stress factor that limits seed germination and early seedling development, especially in arid and semi-arid regions that are increasingly affected by climate change. Seed priming offers a promising strategy to enhance salt stress tolerance. While essential oils have been widely studied, the potential of hydrolates, aromatic water by-products of essential oil distillation, remains largely unexplored. This study investigates the effects of laurel (Laurus nobilis) and rosemary (Rosmarinus officinalis) hydrolates, alone and in combination, as natural seed priming agents to mitigate salt stress in wheat (Triticum aestivum L.). Our results show that laurel hydrolate significantly improved germination rate, speed, and seedling vigour under both control and moderate salinity (50 mM NaCl), while rosemary hydrolate had a limited impact on germination but supported seedling growth, particularly coleoptile elongation. Combined treatment further enhanced germination, indicating a potential synergistic effect. Under severe salinity (100 mM NaCl), however, none of the treatments restored germination to control levels. GC-MS analysis revealed that laurel hydrolate was rich in eucalyptol and linalool, monoterpenes known for their antioxidant and membrane-stabilising properties, supporting enhanced phenolic biosynthesis and oxidative stress mitigation. In contrast, rosemary hydrolate contained higher levels of camphor and verbenone, compounds associated with phytotoxicity and less effective ROS regulation. The biochemical analysis confirmed that laurel hydrolate consistently increased phenolic content, while total protein content remained largely unaffected across treatments. Overall, this study highlights the potential of laurel hydrolate as a low-cost, eco-friendly biostimulant to improve wheat performance under moderate salt stress, offering a sustainable approach for salinity-affected agriculture.